I am designing a wordpress theme (this is my first theme). My design doesn't show correctly in IE.

Here is the design in Firefox (in which sidebar is showing up properly)



Here is the Design in Internet Explorer.



CSS code for footer & innersidebar (the white area in sidebar)

Code:
#footer {
float:left;
width:800px;
clear:both;
font-weight:bold;
color:#FFFFFF;
background:#000000;
height:20px;
text-align:center;
}

.innersidebar {
float:right;
width:180px;
margin-right:15px;
background-color:#FFFFFF;
color:#FF0000;
}
Would you please advise me how can I fix this problem.